Root canal filling device including releasably reusable inserter tool

ABSTRACT

A root canal filler assembly including a single use obturator and a multiple use elongate inserter tool is disclosed. The oburator includes a metallic core and a plasticizable coating, preferably formed of gutta percha. One end of the metallic core extends beyond the plasticizable coating to support a connector assembly. The multiple use inserter tool is removably connectable to the oburator to insert, remove, adjust, and reposition the obturator in a root canal. The inserter tool includes at one end a connector assembly which engages the obturator and at the other end a handle to facilitate manipulation of the assembly by the dentist. The elongate inserter tool may be reused as required, both to remove or reposition a previously inserted obturator and to insert additional obturators in other root canals. 
     A method of filling and sealing a root canal employing the disclosed root canal filler assembly is also provided.

TECHNICAL FIELD

The present invention relates generally to devices and methods fortreating root canals. More particularly, the present invention relatesto a two part root canal treatment device including a single use portionfor filling the apical end of a root canal and a multiple use portion ofwhich temporarily engages the single use portion to insert it into theroot canal and is then removed.

BACKGROUND OF THE INVENTION

A tooth is a calcified structure that includes a crown portion connectedto one or more relatively long root portions which extend through thegum and into the jawbone. The roots of a tooth usually curve slightly asthey extend away from the tooth crown to culminate in a relatively thinapex. Each tooth root includes a root canal with rough-surfaced innerwalls. In a healthy tooth, the pulp chamber and root canal are filledwith pulp, which includes the tooth blood supply and nerve. Dentalproblems which involve the tooth roots, particularly the root canals,are quite common.

When a tooth becomes diseased or damaged as a result of infection,abscess formation, periodontal disease; trauma to the tooth or a deepcavity, removal of the tooth's pulp may be the only way to save thetooth. The damaged or diseased pulp, which contains the nerves and bloodsupply for the tooth, can cause additional damage or infect surroundingtissues unless the tooth is treated to remove the affected pulp.Treatment of the tooth involves making an opening in the the crown ofthe tooth to allow access to the pulp in the tooth pulp chamber androot. The pulp is removed, and the canal and pulp chamber cleanedthoroughly and medicated, if required, to prevent further infection.Once all infection is gone, the root canal and pulp chamber are filledand sealed, and the crown of the tooth is restored. The extent of thecrown restoration necessary may vary from a simple "filing" if the toothis structurally sound to a full crown replacement supported by one ormore posts placed in the root canal.

The root canal treatment preferred by endodontists involves filling theroot canal and pulp chamber with an inert biocompatible material toprevent further complications. Unless the pulp is removed and the rootcanal refilled with a biocompatible, inert material, the damaged pulpcould serve as a medium for bacteria or act as a "foreign body," and theroot could become further inflamed or infected. It is especiallyimportant to insure that the root apex is sealed and filled properly toprevent the intrusion of fluids from the tissue surrounding the rootinto the canal, or to prevent the extrusion of filler material into thistissue.

When problems with the tooth root and the root canal arise, there may bedamage to the crown of the tooth as well. Crown damage could also occurduring drilling of the tooth to treat the root canal if the structuralintegrity of the tooth has been affected by the disease, trauma orinfection that originally caused the root canal problem. To restore thecrown may require the placement of one or more posts within the tooththat extend into the root canal, to anchor a crown or other restorativework. Such posts are used not only to assist in the total restorationand rehabilitation of the tooth. but are sometimes placed in the rootcanal as an additional tooth support, even when crown restoration is notrequired. Posts that are located in the root canal are typicallycemented in place after the pulp is removed before the root canal isfilled. Consequently, their removal can be difficult.

In some cases, additional treatment or restorative work must beperformed on the tooth some time after the root canal has been filledand sealed. This may require the removal of the root canal filling toallow the necessary treatment or restoration of the tooth. Until now,root canal fillings could only be removed with considerable manipulationof the root canal and tooth. These procedures and the use of potentiallytoxic substances, such as chloroform, increase the attendant risk ofdamage to surrounding tissues resulting from available root canaltreatments.

Various and diverse devices and methods have been used to fill andrepair root canals. Filler points or cones made from gutta percha orsilver, posts screwed into the jawbone, and obturators, such as thosemarketed under the name THERMAFIL by Tulsa Dental Products, have beenused to fill the apical portion of the root canal. Pastes and injectablegutta percha have been used both in conjunction with the above devicesand separately to fill root canals. However, all of these devices andmethods have inherent disadvantages. are biocompatible, pure guttapercha points are overly flexible and lack rigidity, which causes themto bind in the root canal during insertion. Consequently, a gutta perchapoint often cannot be inserted as far into the root canal as it shouldgo. In addition, it is possible to insert such a point farther into theroot canal than is desirable. If this occurs, a pure gutta percha pointis extremely difficult to retrieve and remove. Other available pliablebiocompatible materials, such as injectable gutta percha and pastes, aredifficult to control at the root apex and may be forced through the rootapex. In addition, the injectable pastes sometimes tend to resorb.

Kinsman U.S. Pat. No. 674,419 and Miller U.S. Pat. No. 1,463,963 arerepresentative of early solutions to the problem of filling a rootcanal. These patents disclose the use of gutta percha points havingmetallic cores for this purpose. Although these fillers have morerigidity and may be somewhat easier to control than pure gutta perchapoints, the metallic core points described in these patents aredifficult to retrieve if pushed too far into the root canal. If thecanal requires retreatment at a later date, moreover, this type of guttapercha metal point is very difficult to remove.

Some rigid metallic fillers, for example silver points, tend to corrodeover time, as they are not highly biocompatible with root canalenvironment. These elongated point devices, moreover, are not flexibleand cannot adequately conform to the curvature of the tooth root canalto fill and seal the canal effectively. Also, it may be difficult toplace a post in the same canal with a silver point or cone. If the pulpis replaced with a silver point which extends substantially the entirelength of the canal, the incisal or occlusal end of the point must beremoved to accommodate a post. Removal is usually accomplished bydrilling. However, not only is it difficult to drill through the silver,but such drilling vibrates the silver point so that damage to the apicalseal is extremely likely. Consequently. It is necessary to notch thesilver point prior to insertion in the canal so that the top of thepoint may be broken off with dental pliers rather than drilled. Finally,the retrieval and removal of these points for subsequent treatment ofthe tooth is not easily accomplished.

One recently proposed root canal filler device is a one piece endodonticobturator which includes a calibrated stainless steel carrier shapedlike a standard endodontic file and coated on one end with alpha guttapercha. This carrier is provided in a range of different sizescorresponding to standard endodontic file sizes. A handle on one end ofthe carrier assists the dentist in the insertion of this obturator intothe root canal. An endodontic file must first be inserted in the rootcanal to obtain the approximate distance the obturator must be insertedinto the root canal. Once this distance is determined. A rubber stop onthe carrier is positioned at the calibration on the carriercorresponding to this distance. The gutta percha portion of theobturator is then heated until it begins to expand and becomesplasticized, and the obturator is inserted into the root canal to thelevel indicated by the rubber stop. The stainless steel carrier providedwith this device is significantly longer than required to fill the rootcanal. Consequently, the excess carrier shaft must be cut off andremoved. This is done with a fissure but in a high speed hand piecewhile the shaft is in the root canal. The excess shaft, handle and stopare then removed to allow vertical condensation of the gutta percha.

While the aforementioned endodontic obturator represents an improvementover previously available root canal filler devices, it still suffersfrom some significant disadvantages. Because the gutta percha tip isheated prior to insertion into the root canal. it is possible to pushthe end of the stainless steel carrier shaft through the warmed guttapercha during insertion so that exposed metal rather than plastic guttapercha contacts the root apex. If too much force is exerted duringinsertion. not only could the metal be exposed, but the metal shaftcould actually penetrate the root canal apex. In neither instance wouldan effective apical root canal seal be formed Severing the carrier shaftto the proper length with a fissure bur in a high speed hand piece afterthe obturator has been inserted into the root canal subjects theobturator to undesirable high speed vibrations that could vibrate thedevice loose and also traumatize the tooth. Cutting this carrier shaftinside the mouth is also more difficult for the dentist. In addition,this prior art endodontic obturator requires special treatment so thatthe root canal can accommodate both the obturator and a post, if one isrequired for restorative work. The stainless steel carrier shaft must beproperly notched somewhat below the level of he rubber stop and handleprior to insertion and the shah broken off after insertion. Too large anotch will weaken the shaft so that it could break during insertion.while too small a notch may prevent breakage of the shaft at the propertime.

Moreover, the removal of this obturator from the root canal can only beaccomplished with difficulty. If the obturator is notched and separatedwell down into the root canal, its removal is virtually impossible. Thehandle portion of the obturator is permanently removed when the carriershaft is severed, and, therefore, cannot be reconnected to the shaft. Asa result, removal of the obturator requires the application of heat orsolvents to the gutta percha and instruments to the carrier shaft toextract them from the root canal. Consequently, subsequent treatment atool canal into which such an obturator for has been inserted can beperformed only after a series of steps potentially traumatizing to theroot canal, tooth and surrounding tissue.

Finally, if the aforementioned obturator is inadvertently thrust pastthe apical foramen, it is almost impossible to pull the metal core backinto the root canal without leaving the already plasticized gutta perchabehind.

Another prior art root canal filler is described in Tosti U.S. Pat. No.3,813,779 discloses a threaded post which is screwed through the toothand into the jawbone to fill the root canal and anchor the tooth. Apartfrom the likelihood of unnecessary trauma to the tooth and severecomplication should the procedure not be properly performed, this deviceis not likely to provide an effective root canal seal.

The prior art devices for filling root canals, therefore. suffer fromnumerous drawbacks. Often, these devices are too flexible so thatpositioning and repositioning them is difficult. More rigid devices areunable to adequately fill and seal the apical region of the root canalas they can not conform to the curvature of the tooth root. Many of thedevices are inserted, positioned, or customized within the root canalsin ways that unduly traumatize the tooth, gums, jawbone, and surroundingmouth areas. Moreover, if these devices are improperly manipulated,further trauma and complications could result. Available tools used toinsert available root canal filler pins or points are not easy to use.None of the known devices and tools for filling root canals, moreover,is easy to use, permits the filler to be first attached and subsequentlyreattached to an inserter tool for adjustment or removal of the filler,or employs a reusable inserter.

Thus, the prior art fails to provide a root canal filler deviceincluding a single use substantially flexible filling cone or obturatorthat conforms to both the relatively long length and the curvature of atooth root canal to effectively seal and fill the root canal and thatcan be adjusted to the proper length after radiographic confirmation ofplacement within the root canal, wherein the obturator is removablyreattachable to a multiple use inserter tool whereby the obturator isinserted into a root canal so thai after the inserter tool has beenseparated from the obturator, the inserter can be easily reattached tothe obturator to reposition or remove it, as required. There is a need,therefore, for such a two part root canal filler device including asingle use obturator for effectively filling and sealing the root canaland a multiple use insertion tool for inserting and removing theobturator as required for the treatment and ongoing management of rootcanal problems.

SUMMARY OF THE INVENTION

It is an object of the present invention, therefore, to provide a twopart root canal filler device that includes a single use filler portionremovably reattachable to a multiple use inserter portion whichfacilitates both the initial filling and sealing of a root canal and theongoing management of root canal treatment.

It is another object of the present invention to provide a root canalfilling device that includes a filler portion that can be cut to thespecific length required to fill and seal the root canal at a locationoutside the mouth.

It is another object of the present invention to provide a root canalfilling device that includes a filler portion that will effectively sealthe root canal without corroding or irritating the surrounding tissue.

It is another object of the present invention to provide a two part rootcanal filling device that includes an single use filler portionincluding a relatively flexible coating formed of a pliablebiocompatible material which substantially conforms to the shape of theroot canal when inserted therein and a relatively rigid core formed of abiocompatible metal which is releasably engaged by a multiple useinserter tool which guides the filler portion to its proper position inthe root canal.

It is another object of the present invention to provide a root canalfilling device that includes a single use, elongate, cone shaped fillerportion that produces a consistent, effective apical seal, allows foreasy placement and adjustment during obturation of the root canal, andis easily retrieved if the root canal requires retreating.

It is another object of the present invention to provide a root canalfilling device which both effectively seals and fills a root canal andaccommodates a dental post in the canal.

It is a further object of the present invention to provide a method offilling a root canal wherein a single use root canal filler formed of abiocompatible flexible coating and a biocompatible rigid core isinserted into the canal of a tooth root by a temporarily attachedmultiple use inserter tool to seal and fill the root canal along adesired distance from the apex, and the inserter tool is easily andnontraumatically removed from the canal.

It is yet a further object of the present invention to provide a methodof filling a root canal wherein the canal is quickly and effectivelysealed and filled to the proper level in a manner which minimizes traumato the tooth and mouth tissues.

It is a still further object of the present invention to provide atreatment method for tooth root canals whereby a single root canal canbe effectively filled and sealed during a first treatment and the fillereasily removed and the canal retreated during one or more subsequenttreatments.

The aforesaid objects are achieved by providing a two part root canalfiller assembly that includes a single use obturator which issufficiently flexible and plastic to be inserted into the root canal toconform to the shape of the canal so that it seals the apex and fillsthe canal to a predetermined distance from the apex. A multiple useinserter tool which temporarily and removably engages the obturator isprovided to assist the endodontist in inserting one or more suchobturators into the root canal and positioning the obturator orobturators properly within the canal to fill the canal as required. Theinserter tool is then easily disengaged from the obturator and removedfrom the root canal with substantially no trauma to the canal orsurrounding structures. The obturator includes an elongated metal corewhich is coated with a flexible plasticizable material along its apicalend. A portion of the core extends beyond the coating to form anuncoated obturator shaft, which includes a connector assembly andterminates in a point at its insertion end. The inserter tool is anelongated rod, one end of which is a connector end with a connectorassembly which engages the corresponding connector assembly on theinsertion end of the obturator shaft. The opposite end of the insertertool includes a handle having substantially the same configuration as aconventional root canal file and a measuring means for ascertaining thedistance the inserter tool has been inserted into the canal.

The present invention additionally provides a method for filling andsealing a tooth root canal using the above-described assembly, whereinthe obturator threaded shaft is screwed into the threaded recess in theinserter tool to temporarily connect it to the inserter tool, and thisassembly is inserted into the canal of the root of a tooth so that thecoated apical end of the obturator seals and fills the apex of the rootcanal to the required distance. Heat is applied to the plasticizablecoating to cause it to become plastic and conform to the irregularsurfaces of the root canal, thus insuring that the canal is completelyfilled and sealed. The inserter tool is then disconnected from theobturator threaded shaft and removed from the canal. If removal of theobturator is subsequently required, the inserter tool is simplyreinserted into the canal and reconnected to the obturator so that theconnector assemblies are teengaged. Because repeated removal of theobturator can be accomplished readily and easily, any cutting requiredto shorten the obturator can be done outside the dental patient's mouth.

Various additional advantages and Features of novelty which characterizethe invention are further pointed out in the claims that Follow.However, for a better understanding of the invention and it advantages,reference should be made to the accompanying drawings and descriptivematter which illustrate and describe preferred embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut away side perspective view of the root canal fillerassembly of the present invention inserted in the root canal of a tooth,wherein the assembly components are temporarily connected.

FIG. 2 is a cut away side perspective view of the root canal assembly ofthe present invention wherein the assembly components have beendisconnected.

FIG. 3 is a partially cut away side view of the connector structures ofthe two part root canal filler assembly of the present invention;

FIG. 4 is a partially cut away side view of another embodiment of thetwo part root canal filler assembly of the present invention;

FIGS. 5a-5d illustrate the root canal filling method of the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The root canal filler assembly of the present invention provides theendodontic specialist with a treatment device and method for easily andeffectively performing the initial treatment and managing the ongoingcare of problems associated with the roots of the teeth. In the past,the treatment and care of these problems has been neither easy noralways as effective as could be desired. Until the present invention,once a root canal filler was inserted into the canal it could beretrieved only with difficulty, which usually resulted in some degree oftrauma to the tooth and surrounding structures in the dental patient'smouth. The present invention offers an alternative to previouslyavailable root canal devices and filling procedures that is not onlynontraumatic and, therefore, more easily tolerated by the dentalpatient, but is also extremely effective and reliable in filling andsealing the root canal.

Referring to the drawings, the root canal filler assembly of the presentinvention is shown n in FIGS. 1 and 2 inserted in the root canal oftooth 10. Although the tooth shown is a lower tooth, the assembly isequally effective in filling the roots of upper teeth. The tooth shownin FIGS. 1 and 2 has had much of the crown removed to provide access tothe pulp chamber 12 and root canal 14. The pulp, including the bloodsupply and tooth nerve has already been removed from the root canal aspart of the treatment of the tooth shown in FIGS. 1 and 2, so that thecanal is substantially cleared of this tissue. FIGS. 1 and 2 show aperspective side view of the tooth 10 with a portion of the toothremoved to illustrate clearly the placement of the present root canalfiller assembly 16 in the canal 14.

Although the walls 18 of root canal 14 are shown as being relativelystraight and smooth, in actuality the canal may curve somewhat, and thewalls have a rough irregular surface. These features have presentedobstacles to the proper filling and sealing of root canals which thepresent invention has overcome.

The root canal filler assembly 16 is illustrated in FIG. 1 as it wouldappear following the initial insertion of obturator 20, the fillerportion of the assembly, into the apex 15 of the root canal 14. Theobturator 20 is shown temporarily connected to the inserter portion,inserter tool 22. The obturator 20 has an apical end 24, which contactsthe apex 15 of the root canal, and an inserter end 26, which will bedescribed in more detail below in connection with FIG. 3. The insertertool has a connector end which engages the insertion end 26 of theobturator 20 at joint 27 within the root canal. The opposite end 30 ofthe inserter tool 22 extends beyond the pulp chamber 12 to support ahandle 32.

Although other handle configurations could be employed, the three partsubstantially cylindrical arrangement shown in FIGS. 1 and 2 ispreferred. This configuration is substantially identical to that of aconventional root canal file and, as a result, provides the dentist witha familiar structure. The tactile familiarity provided by thisparticular handle further enhances the efficiency with which theassembly can be used to fill and otherwise treat root canals, whichmust, of necessity, be performed in very limited space. The handle maybe formed of metal, rubber, or a plastic, such as polyvinyl chloride(PVC). However, a metal handle would only be selected if the root canalfiller device was intended to be used with a heat applicator.

The root canal filler assembly also preferably includes a stop 34slidably mounted on the inserter tool 22 to move axially along theinserter between the handle 32 and the top of the pulp chamber 12. Stop34, which is preferably formed of rubber or a similar flexible,substantially inert material, is employed as a measuring gauge tofacilitate the assessment of the correct placement of the obturator 20at the root canal apex 15. The manner in which stop 34 performs thisfunction will be explained herein below.

Unlike the prior art, the present root canal filler assembly includestwo major components which are temporarily connected prior to theirinsertion into the root canal and are then disconnected within the rootcanal once obturator 20 has been placed in an optimum sealing position.FIG. 2 illustrates the components of the root canal filler assembly 16after they have been disconnected, but before the inserter Tool 22 hasbeen removed from the root canal. Connector end 28 of inserter tool 22has been removed from its connection with inserter end 26 of theobturator 20 and is shown spaced beyond the terminus 36 of obturalor 20.Terminus 36, which will be discussed in detail in connection with FIG.3, is telescopingly received inside the inserter tool 22 when theobturator 20 is connected to the inserter tool and, thus, is not visiblewhen these components are connected as shown in FIG. 1. Once theinserter tool 22 is separated from the obturator 20 as shown in FIG. 2.the obturator is generally intended to remain permanently in place inthe root canal 14. However, achieving the proper position of theobturator in the canal may at times be difficult due, for example, tothe curvature of the tooth root or the angle of access to the rootcanal. Removal of the obturator from the root canal and its reinsertioninto the root canal are greatly simplified by the present invention. Theinserter tool 22 is simply reconnected to the obturator 20 to form theunitary structure of FIG. 1, and the handle 32 can be employed to easilyextract the assembly from the canal. Reinsertion into the canal islikewise readily accomplished. This arrangement is especially wellsuited to root canals that previously were extremely difficult to filland seal in a manner which achieved an optimum apical seal.

In addition, the temporary easy disconnect-reconnect feature of thepresent root canal filler assembly 16 eliminates the traumaticseparation which accompanies the unitary permanently connected prior artfiller devices.

Filler 3 illustrates in detail the temporary connect-disconnect featureof the present root canal filler assembly which renders the insertertool 22 capable of repeated use. As noted above, the assembly 16includes two parts: a multiple use inserter tool 22 and a single useobturator 20. The inserter tool is designed to be reused a number oftimes to insert a member of obturators into one or more tooth rootcanals during a single treatment session. The filling of teeth withmultiple root canals may require the insertion of more than oneobturator like obturator 20. In this case, a single inserter tool 22 canbe connected to each obturator in turn to position it in the root canaland then disconnected and removed from the canal. The inserter tool 22can also be cleaned and sterilized for reuse at a later time.

The inserter tool 22 is an elongated shaft and, as discussed inconnection with FIGS. 1 and 2, includes a handle receiving end 30 and aconnector end 28. The inserter tool shaft may be formed of metal,plastic or any similar sterilizable material having sufficient rigidityto provide a positive connection with obturator 20 and to insert theobturator into the apex 15 of root canal 14. An inserter tool having ashaft that is approximately 12 to 15 mm in length has been found tofunction most effectively.

The connector end 28 of inserter tool is formed with a recess 38 whichis shown partially cut away in FIG. 3. Recess 38 includes one part of aconnector assembly 40 which temporarily, but securely, engages acorresponding connector assembly 42 on the obturator 20. Although thepreferred type of connector assembly is formed from a the matingthreaded connector assemblies 40 and 42 shown in FIG. 3, other types ofconnectors that provide the secure temporary connection, disconnectionand reconnection required by the present invention could also beemployed. The longitudinal extent of recess 38 should be sufficient toaccommodate the entire terminus 36 of obturator 20, including theconnector assembly 42.

The obturator 20 has a configuration which generally resembles that of aconventional hand held root canal file. This allows obturator 20 to beheld securely by hand without resort to the cotton pliers customarilyrequired for the insertion of root canal filler structures while it isconnected to inserter tool 22 prior to insertion in the mouth. Obturator20 preferably has a generally cone-shaped configuration to conformsubstantially to the size and shape of the endodontic files commonemployed to file root canals. The obturator 20 includes a rigid core 44which is coated with a flexible plasticizable coating 46, which ispreferably a high melting (beta) gutta percha. This flexibleplasticizable coating extends a substantial distance along the core 44from an apex 24 to terminate just short of the connector assembly 42.The core extends beyond coating 46 to support connector assembly 42 andterminates in terminus 36, which preferably has the inverted cone shapeshown in FIG. 3. This shape has been found particular effective inguiding and engaging the obturator connector assembly 42 into engagementwith inserter tool 22 during reconnection of the assembly within theroot canal. The obturator rigid core 44, therefore, is covered with theplasticizable coating 46 from its apical end 48 to the connectorassembly 42.

It is preferred to form the rigid core 44 from a biocompatible, inertmaterial having sufficient rigidity to allow easy insertion of theobturator into even a very curved root canal. Preferred materialsinclude metals such as titanium and stainless steel. Fluting theexterior of the rigid core material can facilitate condensation of theplasticizable coating as will be discussed below.

The apical end 48 of core 44 is located close enough to obturatorcoating apex 24 to provide sufficient rigidity to insert obturator 20into the root canal all the way to root canal apex 15 without obturatorapex 24 binding or bending back on itself. The core apical end 48 doesnot extend all the ay to the obturator coating apex and, therefore, isnot likely to be pushed through the coating during insertion of theobturator into the root canal.

Since tooth root canals are not uniform in size, but vary, obturator 20is preferably provided in a range of sizes which approximate the sizesof conventional root canal files. Additionally, the configuration of theobturator 20 can be custom sized to fit a root canal by adding differentthicknesses of coating or gutta percha to the rigid core 44. The widthand degree of taper of the obturator can be made to correspond to thewidth and degree of taper of the last endodontic file used to file theroot canal.

The condensation techniques with which the root canal filler assembly 16will be used will determine whether additional gutta percha or likeplasticizable material will be required to completely fill the rootcanal. If regular lateral condensation techniques are employed,accessory gutta percha cones will be required. However, if heat isapplied to the obturator through the handle by a heat applicator,additional gutta percha would not be required. Instead, the heatedobturator could be spun clockwise to condense the warmed gutta perchaapically and laterally. For this to be successful, however, the rigidcore 44 must be properly fluted. Alternatively, a lubricated hollowcondenser could be employed after removal of the handle.

Once a specific size obturator is selected, it is connected to theinserter tool 22 by inserting the terminus 36 into recess 38 until thecorresponding connectors on the obturator and inserter tool are engaged.If connector assemblies 40 and 42 are mating threads as shown in FIG. 3,once the threads of recess 38 contact the threads of obturator core 44,these structures can simply be screwed together.

After the obturator 28 is optimally positioned within the root canal, itis disconnected from inserter tool 22 by unscrewing the inserter tool todisengage the threads of recess 38 from the exterior threads of theobturator 20. If obturator 20 subsequently must be repositioned orremoved, it can be easily reconnected to inserter tool 22 by repeatingthis process.

The obturator 20, which is substantially cone-shaped to conform to theshape of the root canal, may also be referred to as a filler cone. Therigid core 44 is formed of metal, preferably titanium. Implant gradetitanium is used for metallic core 44 because of its very highbiocompatibility and its resistance to corrosion. The use of suchmaterial prevents complications arising from the inadvertent placementof obturator 20 too far into the root canal or from the inadvertentexposure of the metal within the root canal. The plasticizable coating46 is preferably formed of gutta percha because it is malleable and canbe easily plasticized and expands to conform to the various nooks,crannies, and irregularities in the root canal surface. However, anysuitable thermoplastic material which is biocompatible and has thephysical properties required to provide an effective root canal seal andfiller could also be employed.

Disk-shaped stop 34 (FIGS. 1 and 2), as described above, is used as ameasuring device to provide an approximate measurement of the length ofthe approximately 18 mm in length. Thus, stop 34 is positioned oninserter tool 22 approximately 18 mm from the end of filler assembly 16as measured from the apex 24 of obturator 20. When stop 34 approachesthe crown of the tooth during insertion of the assembly, the dentistknows that the apical environment of the root canal has been reached bythe obturator apex 24. This reduces the incidence of long or shortplacement of obturator 20 within the root canal. Alternatively, insertertool 22 may be provided with integral numbered or colorcoded markingsextending axially from handle 32 to estimate the length of a root canal.

Although obturator 20 is selected to be as close in size to the diameterof the root canal as possible, it will never fit exactly. Moreover,since the root canal walls are not perfectly smooth, steps must be takento insure that the plasticizable coating 46 will completely fill thecanal. Lateral condensation techniques can be used to fill all of theirregularities in a root canal. According to this method, an obturator20 is inserted into a root canal. After it is properly placed within theroot canal, a conventional spreader tool (not shown) is inserted intothe root canal and is forced between the wall and the obturator to putlateral pressure on the plasticizable coating 46 to contort and mold itinto the irregularities of the root canal surface. After the spreadertool is removed, if the root canal is not filled, a conventionalaccessory gulta percha cone may be inserted into the root canal and theprocess repeated until the root canal is completely filled. Aconventional plugger tool (not shown) may also be used vertically tocompress excess plasticizable coating 46, thereby further insuringcomplete sealing of the root canal and the root apex.

The present root canal filler assembly is vastly superior to prior artdevices. The obturator 20 is strong enough to be placed in a root canalwithout bending back on itself or binding on the walls of the canal. Theremovable, reusable inserter tool 22 permits easy adjustment andcorrection of the ebturator placement if it is placed too far or not farenough into the root canal. Additionally, the obturator 20 can be placedm the canal and subsequently removed using inserter tool 22 to providespace for a post, if one is necessary to restore the endodonticallytreated teeth. Removal and repositioning of the obturator 20 aresimplified by the provision of the corresponding connector assemblies 40and 42 on of the obturator 20 and the inserter tool 22. This arrangementallows the obturator and inserter tool to be easily connected,separated, and reconnected as required. The obturator can also beretrieved relatively easily for subsequent retreatment of the rootcanal.

The present root canal filler assembly is easily adapted to accommodatedental posts, if they are required to support crown restorationfollowing filling and sealing of the root canal. To accomplish this, theobturator may be made in two specific lengths, one for use in a rootcanal without a dental post and one for use with a dental post. When aroot canal is to be filled without a post, obturator 20 is provided witha plasticizable gutta percha coating 46 approximately 10 mm in length asmeasured from obturator apex 24. Approximately 1/2 mm of gutta perchaprotrudes pat the apex 48 of the rigid titanium obturator core 44, andthe remaining 91/2 mm of gutta percha extend along titanium core 44 tothe connector assembly 42. The distance between the end of coating 46and terminus 36 of the obturator core is about 17 mm. Preferably,substantially the entire 17 mm of the titanium obturator core isprovided with threads or another connector structure.

When the root canal is to have a post inserted after it is filled,obturator 20 preferably is provided with about 5 mm of plasticizablecoating 46, approximately 1/3 mm of this protrudes past the core apex4-8, and the remaining 42/3 mm covers the rigid core 44. In thisinstance, preferably approximately 1-3 mm of rigid (titanium) core 44extends beyond the coating 4-6. Most of this length will preferablysupport the connector assembly 41 and will terminate in pointed terminus36. This particular obturator is specifically sized so that it does notrequire cutting after insertion into the root canal to accommodate apost. This eliminates completely the traumatic notching and twisting ofthe obturator to shorten it after it has been inserted into the rootcanal required by prior art root canal filling devices.

Obturator 20 is preferably inserted into root canal 14 unheated and thenmay be laterally condensed without heating to spread the gutta percha sothat it fills the canal. Alternatively, optimal filling of the canal maybe achieved by using a heating device attached to inserter tool 22 by aclip or the like to conduct a standard, controlled amount of heat fromthe inserter tool through the obturator along the metal core 44 tosoften the gutta percha coating 46 before condensing the gutta perchawith a spreader or plugger lubricated with alcohol. Heating the guttapercha outer coating 46 after obturator 20 is inserted into the rootcanal eliminates the possibility that the titanium core will be pushedout of the gutta percha coating or that the gutta percha will separatefrom the titanium during insertion of the filler assembly into the rootcanal as is likely with prior art devices.

In one alternative embodiment shown in FIG. 4, plasticizable coating 46,includes two layers of plasticizable material, one of which has a highermelting point than the other. It is preferred to form the inner layer 50of high melting gutta percha and the outer layer 52 of low melting guttapercha. Ibis facilitates the use of heating devices instead of or inaddition to lateral condensation techniques to spread the gutta perchato seal and fill the canal effectively. A heating device, similar tothose made by Hygienic Corporation, can be employed to heat the fillerassembly 16. The low melting gutta percha outer layer 52 will becomeplastic and flow to fill all of the root canal wall surfaceirregularities. P The high melting gutta percha inner layer will notbecome plastic at the same temperature and, therefore, will continue toprovide some rigidity to the apex 24 and to provide a protective layeraround the apical tip 48 of the titanium metal core. Forming the coating46 of two layers allows the heating of the coating to a well controlledpredetermined temperature which is sufficiently high to plasticize outerlayer 52 without plasticizing inner layer 52. This arrangement alsopermits the heating of the filler assembly prior to insertion in a rootcanal without the risk of exposing the metal core which is inherent inprior art filler devices. The rigid metal core 44 will be protected bythe layer 50 of high melting gutta percha and will not be easily pushedthrough the high melting gutta percha coating layer 50 to leave anunsealed exposed section of titanium. The use of differentially meltingouter layer 52 and inner layer 50 permits even an uncontrolled heatsource, such as a Bunsen burner or an alcohol torch to be used to heatthe gutta percha coating. Even such an uncontrolled heat source isunlikely to plasticize inner layer 50. Heating may also be combined withlateral condensation techniques to plasticize the two layer gutta perchacoating and assist its condensation so that the root canal is completelyfilled and sealed.

In another form of the present invention, a coating of metal plasma maybe sprayed on the metal core 44, thereby roughening and increasing thecore surface area to provide a better retentive surface for the guttapercha or other plasticizable coating. Alternatively, the metal maysimply be sandblasted to create the necessary retentire surfaceroughness.

A root canal can be filled with the assembly of the present inventionusing a series of simple steps which are illustrated in FIGS. 5a-5d.FIG. 5a shows a crossectional side view of a tooth 60 in place in themouth. The tooth root 62 extends well into the jaw bone 64. The oppositeend of the tooth terminates in a crown 66 covered with a layer of enamel68. Gum tissue 70 covers the jaw bone 64 and helps to hold the toothsecurely in place. A pulp chamber 72 is located in the center of thetooth and extends longitudinally to the root apex 74 to form a rootcanal 76. If the pulp becomes damaged as a result of infection, trauma,disease or the like, it must be removed to prevent further damage to thetooth and surrounding tissues.

Removal of the pulp is accomplished by drilling through the tooth crown66 to reach the pulp chamber 72. The opening formed must be large enoughto provide adequate access to the pulp chamber to allow complete removalof the damaged or diseased pulp and cleaning of the pulp chamber androot canal. FIG. 5b illustrates a tooth which has been drilled to removea portion of the crown 66 and expose the pulp chamber 72. The amount oftooth crown removed can range from a relatively small section to theentire crown, depending upon the integrity of the tooth. The extent towhich the crown must be removed will determine whether one or moredental posts will be required to support crown restoration performedsubsequent to the root canal treatment. As discussed above, therequirement for a post will affect the length filling cone or obturatorselected to fill the canal.

A filler cone or obturator 80 of the appropriate length is selected andconnected to an inserter tool 82 by inserting pointed terminus of theobturator into the recess in the inserter tool as discussed above inconnection with FIGS. 1 to 3. The obturator 80 is secured to insertertool 82. The handle 83 of the inserter tool is then used to guide theobturator into root canal 76, as shown in FIG. 5b, by first insertingthe obturator apex 84 into the canal. As indicated above, because of thestiffness of the apex 84, it will not bind or bend back on itself duringinsertion. As long as obturator 80 remains connected to inserter tool 82the obturator can be positioned, repositioned, adjusted, or removed fromroot canal 76 as necessary merely by manipulating the inserter tool.

The assembly is inserted into the root canal so that the desired lengthof obturator 80 can be determined, either by positioning a slidable stop85 or using calibrations on the inserter tool 82 as described inconnection with FIG. 1. The assembly is then removed from the dentalpatients's mouth, and the excess length of obturator titanium core (notshown) is cut off, preferably using a Joe Dondy disc or similar tool.Ideally, after cutting, the obturator core extends approximately 2 to 3mm above the gutta percha coating into the tooth pulp chamber when theapex 84 of the obturator 80 is properly placed in the root canal apex74, as shown in FIG. 5c. This eliminates the possibility of vibratingand shaking loose the obturator as may occur if a bur is used to cut theobturator after placement in the root canal. Additionally, it is mucheasier to cut the obturator outside the mouth rather than after theobturator is inserted into the pulp chamber of the root canal where thecutting can become very messy.

Once the obturator 80 is properly positioned in the root canal as shownin FIG. 5c. the obturator plasticizable coating may be heated to apredetermined temperature to plasticize it so that it expands to filland seal the root canal. Heating may be accomplished using any ofvarious heating devices adapted to heat the coating in the root canal.Lateral or vertical condensation techniques may also be used, either inaddition to or instead of heating. These techniques involve inserting aspreader or plugger into the root canal to force the gutta percha orother plasticizable coating into all of the surface areas of the rootcanal.

After obturator 80 is properly positioned in root canal 76, as shown inFIG. 5c, inserter tool 82 is separated from the obturator bydisconnecting the respective connector assemblies on the inserter tooland the obturator. If a single obturator 80 is inserted and condensedand does not fill the root canal to the desired extent, additionalobturators may be connected to the inserter tool and then inserted andcondensed as necessary until the root canal is filled.

Once the root canal is filled to the necessary level, the inserter tool82 can be removed simply by disconnecting it from the obturator andpulling it out of the root canal. If it is necessary to repositionobturator 80 after inserter tool 82 has been removed, the inserter tool82 12 is easily reinserted into the root canal to engage obturator 80.The preferred obturator and inserter tool configuration shown in FIG. 3facilitates the engagement of these components. The two components arethen reconnected, and the appropriate adjustment performed.

After obturator 80 is located in its final, desired position, the rootcanal 76 must be sealed and the tooth crown restored with a restoration88 as shown in FIG. 5d. A small removable brightly colored "cap" ofplastic or gutta percha can be made to place over and cover the threadsof the connector assembly 42 placement of the obturator to preventcement or other restoration materials from blocking access to thethreads if it became necessary to re-attach the inserter tool at somefuture time.

Restoration of the crown will, of course, depend on the extent to whichthe crown was removed lo provide access to the root canal.

If a post is required to support crown restoration, the post can beinserted after one or more obturators have been placed as required tofill the apical portion of root canal. If a post is to be inserted intothe root canal at a later time, the gutta percha sealant 86 can beseared off down to the level of the obturator 80.

Numerous characteristics, advantages, and embodiments of the inventionhave been described in detail in the foregoing description withreference to the accompanying drawings. However, the disclosure isillustrative only and the invention is not limited to the preciseillustrated embodiments. Various changes and modifications may beeffected therein by one skilled in the art without departing from thescope or spirit of the invention.

INDUSTRIAL APPLICABILITY

The root canal filler assembly of the present invention is a substantialimprovement over known root canal filling devices. The filler assemblyof the present intention will find its primary application and use inthe field of endodontics where it may be effectively employed ininitially treating and in managing the ongoing treatment of root canals.

I claim:
 1. A root canal filter assembly for inserting a biocompatiblefiller material into the canal of the root of a tooth to fill and sealthe canal following removal of the tooth pulp and treatment of thecanal, said filler assembly comprising:(a) single use filler meansconforming substantially to the configuration of the root canal to filland seal the root canal from the apex of the root to a desired distanceaway from the apex, said single use filler means having an apical end,and an insertion end, wherein said insertion end includes a threadedfiller connector assembly, and (b) multiple use inserter means forinserting said filler means into the root canal and properly positioningsaid filler means in the root canal, said multiple use inserter meanshaving a connector end and a handle end wherein said connector endincludes a threaded inserter connector assembly configured to threadedlyand removably engage the threaded filler connector assembly of saidfiller means.
 2. The root canal filler assembly of claim 1, wherein saidfiller means includes a relatively rigid longitudinal core portion and arelatively flexible plasticizable coating portion extending axiallyalong said core portion from said apical end to terminate short of saidinsertion end to leave said core portion exposed al the insertion end ofsaid filler means.
 3. The root canal filler assembly of claim 2, whereinsaid filler connector assembly is positioned on said exposed coreportion.
 4. The root canal filler assembly of claim 3, wherein saidinserter connector assembly is positioned interiorly of the connectorend of said insertion means.
 5. The root canal filler assembly of claim4, wherein said inserter connector assembly and said filler connectorassembly comprise correspondingly threaded sections of said insertermeans and said filler means is threadedly engaged by said insertermeans.
 6. The root canal filler assembly of claim 5, wherein said fillermeans core portion is formed of metal.
 7. The root canal filler assemblyof claim 6, wherein said filler means coating portion is formed of guttapercha.
 8. The root canal filler assembly of claim 5, wherein saidfiller means coating portion comprises two layers of differentiallymelting plasticizable material, said innermost layer having a highermelting point than said outermost layer.
 9. The root canal fillerassembly of claim 8, wherein the innermost of said two layers compriseshigh melting gutta percha and the outmost of said two layers compriseslow melting gutta percha.
 10. The root canal filler assembly of claim 1,wherein said inserter means further includes handle means located at thehandle end thereof to facilitate the insertion and manipulation of saidinserter means in a root canal.
 11. The root canal filler assembly ofclaim 10, wherein said inserter means further includes measuring meansfor measuring the distance said filler assembly has been inserted intosaid root canal and assessing proper placement of the filler assembly inthe root canal.
 12. The root canal filler assembly of claim 11, whereinsaid measuring means comprises a stop axially slidable along saidinserter means.
 13. A filling device for refilling a tooth root canalwith a canal filling during treatment of the tooth to permit the canalfilling to be easily inserted, positioned, and removed, said fillingdevice comprising:an elongate filler cone having first and second endsand comprising a relatively narrow tip portion formed at said first end,said elongate filler cone being insertable and adjustable within andremovable from the tooth root canal; removable elongate insertion meansfor inserting, adjusting, repositioning, and removing said elongatefiller cone in the root canal, said removable elongate insertion meanscomprising first and second ends and a handle portion formed at saidfirst end, and said removable elongate insertion means being reusable:and connection means disposed at said second end of said removableelongate insertion means for releasably connecting said removableelongate insertion means to said second end of said elongate filler conesuch that said elongate filler cone can be connected to, removed from,and reconnected said removable elongate insertion means as required. 14.A root canal filling device according to claim 13 wherein said elongatefiller cone is formed with external threads on said second end andwherein said connection means comprises a hollows internally threadedportion formed at said second end of said removable elongate insertionmeans, said elongate filler cone and said removable elongate insertionmeans being releasably, threadably connectable and reconnectabletogether.
 15. A root canal filling device according to claim 14 whereinsaid second end of said elongate filler cone comprises a relativelynarrow tip portion receivable in said hollow internally threaded portionto facilitate connecting said elongate filler cone to said removableelongate insertion means.
 16. A root canal filling device according toclaim 13 wherein said relatively narrow tip portion formed at said firstend of said elongate filler cone is sufficiently rigid to resist bindingor bending back when said elongate filler cone is inserted into a rootcanal.
 17. A root canal filling device according to claim 13 whereinsaid removable elongate insertion means comprises a rigid insertershaft.
 18. A root canal filling device according to claim 17 whereinsaid inserter shaft is formed of metal.
 19. A root canal filling deviceaccording to claim 17 wherein said inserter shaft is formed of plastic.20. A root canal filling device according to claim 17 further comprisingmeasuring means for indicating the approximate length of the root canalto thereby reduce the incidence of long or short placement of saidelongate filler cone within the root canal.
 21. A root canal fillingdevice according to claim 20 wherein said measuring means comprise arubber disk slidably mounted on said inserter shaft near said first endbelow said handle.
 22. A root canal filling device according to claim 13wherein said handle is shaped like a root canal file.
 23. A root canalfilling device according to claim 13 wherein said handle is formed ofplastic.
 24. A root canal filling device according to claim 13 whereinsaid handle is formed of rubber.
 25. A root canal filling deviceaccording to claim 13 wherein said elongate filler cone comprises aninner core layer and an outer shell layer.
 26. A root canal fillingdevice according to claim 25 wherein said inner core layer is formed ofmetal.
 27. A root canal filling device according to claim 26 whereinsaid inner core layer is formed of manlure.
 28. A root canal fillingdevice according to claim wherein said outer shell layer is formed of athermoplastic material.
 29. A root canal filling device according toclaim 28 wherein said outer shell layer is formed of gutta percha.
 30. Aroot canal filling device according to claim 25 wherein said elongatefiller cone further includes a retentive surface formed on said innercore layer.
 31. A method of filling the root canal of a tooth with abiocompatible filler after the tooth has been opened to expose the rootcanal and the canal has been cleared of diseased or damaged pulpcomprising the steps of:(a) selecting an appropriately sized obturatormeans including an elongated rigid core portion, a flexibleplasticizable coating portion covering said core portion to extend fromone end of said core portion axially along said core portion, and athreaded connector assembly at the other end of said core portion forfilling and sealing the apical end of the root canal: (b) temporarilyconnecting the threaded connector assembly of said obturator means to acorrespondingly threaded connector assembly on the connector end of aninserter means for inserting said obturator means into the root canal byscrewing said connector assemblies together to form a tool canal fillerassembly: (c) inserting said root canal filler assembly into the clearedroot canal so that the coating portion of the obturator means ispositioned within the canal to fill and seal the apical end of the rootcanal: (d) disconnecting the inserter means from the obturator means byunscrewing the inserter means threaded connector assembly from theobturator means threaded connector assembly; (e) removing said insertermeans from the root canal to leave the obturator means in the rootcanal, thereby permitting said inserter means to be reused: and (f)sealing the portion of the root canal not filled by the obturator meansand restoring the integrity of the tooth.
 32. The method of filling aroot canal described in claim 31, further including the steps ofremoving the seal formed in step (f), reinserting said inserter meansinto said root canal, screwing said threaded connector assembly of saidobturator means into said threaded connector assembly of said insertermeans, repositioning said obturator means, disconnecting said threadedconnector assemblies, and removing said inserter means from said rootcanal.
 33. The method of filling a root canal described in claim 31,further including the step of, after step (c) but before step (d),heating said obturator means to plasticize said plasticizable coating.34. The method of filling a root canal described in claim 31, furtherincluding the step of, after step (e). inserting a support post intosaid root canal to extend from said obturator means to the toothsurface.
 35. The method of filling a root canal described in claim 31,further including the step of, after step (c) but before step (d). usingmeasuring means to measure the distance said assembly extends to saidroot canal. .Iadd.
 36. A biocompatible filler for insertion into thecanal of the root of a tooth to fill and seal the canal followingremoval of tooth pulp and treatment of the canal, said fillercomprising:a relatively rigid longitudinal core; and a relativelyflexible plasticizable coating extending axially along at least aportion of said core, said plasticizable coating comprising an innermostlayer and an outermost layer of differentially melting plasticizablematerial. .Iaddend. .Iadd.37. The filler of claim 36, wherein theinnermost layer has a higher melting point than the outermostlayer..Iaddend. .Iadd.38. The filler of claim 36, wherein the innermostlayer comprises high melting gutta perch and the outermost layercomprises low melting gutta percha. .Iaddend. .Iadd.39. The filler ofclaim 36, wherein the core is metal..Iaddend. .Iadd.40. The filler ofclaim 39, further comprising a coating of metal plasma on the metal coreunderneath the innermost layer of gutta percha..Iaddend. .Iadd.41. Arelatively flexible, plasticizable biocompatible filler for insertioninto the canal of a root of a tooth to fill and seal the canal followingremoval of tooth pulp and treatment of the canal, said fillercomprising:a first plasticizable material which is essentially solid atroom temperature and which is spreadable in the canal under heat and/ormechanical action so as to flow therein; a second plasticizable materialwhich is essentially solid at room temperature and which is spreadablein the canal under heat and/or mechanical action so as to flow thereinunder substantially different conditions of heat and/or mechanicalaction as compared to said first plasticizable material, wherein saidfirst and second plasticizable materials spread in the canal to fill thecanal during a filling procedure, one spreading prior to theother..Iaddend. .Iadd.42. The material of claim 41, wherein said firstplasticizable material and said second plasticizable material havesubstantially different melting points..Iaddend. .Iadd.43. The filler ofclaim 41, wherein said first plasticizable material comprises arelatively high melting point gutta percha and said second plasticizablematerial comprises a relatively low melting point gutta percha..Iaddend..Iadd.44. The filler of claim 41, wherein said first plasticizablematerial comprises an inner layer of relatively high melting point guttapercha and said second plasticizable material comprises an outer layerof relatively low melting point gutta percha surrounding the layer ofrelatively high melting point gutta percha..Iaddend.